Feedlots have different protocols for receiving cattle, but some things are common to all. Smaller cattle need more care than larger ones. Some feedlots won't even accept calves under 600 pounds, they aren't set up to handle the smaller calves.
Some feedlots medicate calves off the truck with micotil or another drug to help prevent shipping fever. I don't like this practice, but they claim it works for them. Many lots vacinate for everything, ibr, somunus, etc. etc., and if cattle from many areas are accepted this might be necessary. I usually buy from local areas and only give an 8-way booster and a de-wormer, but I am dealing with limited numbers and make the time to watch the calves closely for the first 2 weeks.
If your looking at selling to a particular feedlot, they will tell you what they need done to fit their protocol, and many will pay a premium for pre-conditioned calves. Make sure everything is done properly to assure the feedlot of consistancy.
Jason Trowbridge Southern Angus Farms Alberta Canada